I can explain. When one kills the WoF, Both Hallow and Corruption spread upwards in a diagonal line from where the thing has been killed. You were unlucky enough to have one of your Islands in one of the lines. Also, you're lucky. Punk!!!!

Make your friends spawn on a pressure plate that's wired up to explosives and steal there money

Jump off the top of the map with grav potions. Change at the last instant

Collect a chest of every material/ore/wall/brick in the game

Make a world into a single base made of 5x10 rooms

Drain both oceans into Hell, for the lulz.

Turn the underworld into a giant lava lake thanks to the infinite liquid bug, removing all non-lava blocks from it

Get rid of all the lava in a map

Get rid of all the water in a map

Get rid of all liquids in a map

do a "bare handed" char, which is not allowed to use any armor

Make a lava trap that recharges automatically withing liquid pumps

Try to play Terraria in it's entirety with only 1HP

Research! Discover the mechanics of the game, take a close look to the AI of NPCs (friend and foe) or something else and make a good report/guide about it.

Join the community on the forum

Build biome spheres

Eradicate the corruption

mine every piece of ore

give your npcs their own castles

restart the game from scratch

ave your world for easier commuting, use demonite bricks to show the way!

Create an active volcano in your town and reenact the Pompeii incident from the past.

Create a haunted house

Cover the sky in a background wall.

Make a spooky house with hidden explosives and host a server on it

Explore every cave in the map, and mine all the ores.

Eradicate the corruption ... with only a pickaxe!

Stare at your character and make it move only using the power of your mind!

Go through 5 different keyboards by trying to kill a wyvern in iron armor using a Copper shortsword. One can only rage so much without smashing a keyboard.

Try to train your npc's not to open the door on a blood moon. Destroy some more keyboards.

Turn a world into a wildlife/wildunlife preserve with sectioned off safe-zones between the biome areas kind of like a zoo

Switch your hallowed armor to vanity and replace it with copper armor.

Make a perfect circle. Or something that comes close.

PVP until you get 3 stacks of tombstones

Kill EOC with a wooden bow, no armor, wooden arrows.

Kill EOW with gold shortsword. Armor allowed.

Kill Skeletron with a demon bow with wooden arrows and gold armor.

Torture the guide so much he tries to come back and get vengeance.

Discover the true secret behind stopping your NPCs from opening any door at all. A secret which requires no wiring, no complex building patterns, and no hacking

Create a mod that makes spawns x100.

Make a hellevator right above a floating island, go up to that floating island, remove wings and/or horseshoe, jump down. Repeat and see if you can beat your damage record. Best if tried in a large world.

Replace all Corruption with hallow.

Replace all Hallow with Corruption.

Build a castle out of fire block's.

Bury the guide in dirt.

Create a statue of your favorite statue... Made out of statues.

Create natural pipelines from the ocean(s), use them to remove all lava from hell

1 HP hardcore run with only copper sword

Beat the Wall of Flesh without fighting any of the bosses before it.

Make a huge house that takes up the whole world with everything you think you need in it.

Build a challenging shooting gallery.

Build a chain of machines that kill a rabbit in the end

Trap a clown

Build a player trap that's Hamdrax dynamite and skill proof

Explore a flooded dungeon fully without fighting SkeletronHow? Just remove the walling. It stops the guardian from spawning

Beat any boss while fighting from a small platform at skybridge level

Make it rain slimes all over the world.

Dig a tunnel under Hell.

Build a skybridge entirely by mixing lava and water

Kill a blazing wheel. Kill two at once.

Kill 100 enemies without moving from one spot

Make a giant statue of a bomb, that explodes.

Lead a voodoo demon to a sky island

Make a endless waterfall

Make a endless lavafall

Make bunnies rain from the sky

Make a mimic apocalypse

Play with anti-gravity from no armor to hallowed

Create a giant bunny statue out of bunny statues on platforms

Do the same as 98 with all other statues

Get the arms dealer and the nurse in the same room...alone

Make castle from the left side to right side out of the map, out of silver ore

Make a tConfig mod that adds at least 10 new NPC's

Make and endless bunnyfall

Make a statue of yourself from the bottom to the top of the world, out of bunny statues.

Make a long passageway from the top left of the world to the top right. go down enough to walk through. repeat until at bottom of world.